docs: def loads(self, config, content, prefer=None):
          """ An abstract loads method which loads an instance from some content.
  
          :param class config: The config class to load into
          :param str content: The content to load from
          :param str prefer: The preferred serialization module name
          :raises ValueError: If load handler does not provided handler method
          :return: A dictionary converted from the given content
          :rtype: dict
          """
  
          loader = self._prefer_package(prefer)
          loads_hook_name = f"on_{loader}_loads"
          loads_hook = getattr(self, loads_hook_name, None)
          if not callable(loads_hook):
              raise ValueError(
                  f"no loads handler for {self.imported!r}, requires method "
                  f"{loads_hook_name!r} in {self!r}"
              )
          return loads_hook(self.handler, config, content)